Yahoo!Pilot's Operating Handbook
Power settings in the SF260.

Always refer to the Pilots Operating Handbook for final determination of power settings.

ENGINE OPERATION

Engine Starting

The engine can be started by means of the aircraft battery or by an external power source (28V DC and 150 A).

Starting procedure

Note: If the overnight temperature was below 40 degrees F, or if the battery charge is insufficient, an alternate power source may be used for starting the engine.

Note: During extremely cold weather, it may be necessary to preheat the engine oil before starting.

SPECIAL NOTE: FUEL SELECTOR VALVE ON MAIN TANK.
DO NOT START ENGINE ON A WING TIP TANK

1. Mixture : Full rich.
2. Boost pump : ON.
a. Fuel pressure : Check within the green arc.
b. Low fuel pressure warning light: OFF.
3. Throttle: Pump for two or three strokes (cold engine) then open approximately 1/8 travel forward.
Note: If the engine is warm (as shown by an oil temperature indication in the yellow arc or higher), pump the throttle no more than one time.
4. Propeller: Clear.
Before starting the engine, clear the area 360 degrees around the aircraft and call ”CLEAR”
5. Ignition : Turn to START. When the engine fires, release the switch to BOTH.
6. If the engine does not start after three tries then warm the magnetos and try again.

Ground operation

The engine is air cooled and depends on the forward movement of the aircraft to maintain proper cooling. To prevent overheating on the ground, monitor the cylinder head and oil temperature indicators and observe the following precautions:
- If possible, head the aircraft into the wind.
- Leave the mixture control in full RICH.
- Avoid prolonged idling. When stopped on the ground, use 1200 RPM.
-Do not exceed 2200 RPM until you start your ground run for takeoff.

Air Operation

The engine power available at any time depends on three factors; manifold pressure (throttle setting), RPM (Propeller setting), and mixture.
The pilot must continually monitor the engine instruments to maintain the desired engine performance and to avoid exceeding engine limits.
The engine produces maximum power with the throttle full open and the propeller full INCR RPM (fine pitch). These power settings are used for takeoffs, go-arounds, short duration climbs, and emergency cruise. However, the engine is not designed to maintain these power settings for extended periods of time. The useful life of the engine will be shortened significantly if the engine is operated continuously at high power settings.

The following general rules for engine operation should be observed:
1. To avoid engine damage caused by excessive manifold pressure, avoid continuous high throttle setting (high manifold pressure) situations. A good rule of thumb is to keep the manifold pressure less than the RPM, e.g. with 2400 RPM, do not exceed 24 Hg; with 2500 RPM, do not exceed 25 Hg, etc.
2. To avoid pressure surges within the engine, always make power changes as follows:
a. When increasing power, increase the propeller setting before increasing the throttle setting.
b. When reducing power, reduce the throttle before reducing the propeller setting.
3. Avoid continuous operation with high RpM and low throttle setting. When this condition is necessary, make slow, smooth throttle movements.
4. Never exceed the maximum cylinder hear temperature. (250 degrees C). 5. Maintain the mixture control in the RICH position for takeoff, climb, and full throttle power settings.
6. If rough engine operation or loss of power is noted during takeoff from high elevation airfields, during climbs, or during operations above 5000 feet MSL, the mixture may be over-rich. In this case adjust the mixture only enough to obtain smooth operation. Monitor the cylinder head temperature.
7. Always return the mixture to RICH before increasing the power setting.

Mixture Leaning

When leaning the mixture, use the following procedures:
1. Slowly move the mixture control lever from RICH toward LEAN, no farther aft than the second detent.
2. The manifold pressure should slightly increase, and the engine will begin to run more smoothly, as the mixture is leaned.
3. When a slight engine roughness is noted, move the lever toward RICH until the engine runs smoothly.
4. Monitor CHT closely. Lean mixtures result in higher cylinder head temperatures. Never exceed the maximum CHT. For maximum service life, CHT should be maintained below 224 degrees C.

Note: Rough engine operation due to an over-rich mixture is most likely to be encountered at altitudes above 5,000 feet. Therefore the engine is normally operated at the full RICH position below 5,000 feet. Above 5,000 feet (climbs, descents, and cruise) the mixture may be adjusted for maximum engine efficiency.

Use of Carburetor Heat

Under certain atmospheric conditions at temperatures of 20 to 90 degrees F, it is possible for ice to form in the induction system. This is due to the high air velocity through the carburetor and the absorption of heat from this air by vaporization of fuel. The temperature in the mixture chamber may drop as much as 70 degrees F below the temperature of the incoming air. If this air contains a large amount of moisture, the cooling process can cause precipitation in the form of ice. Ice formation generally begins in the vicinity of the throttle and may build up to such an extent that a drop in power output could result.

A loss of power is reflected by a drop in manifold pressure. If not corrected, the icing condition may cause complete engine stoppage. To avoid this condition, the carburetor is supplied with heated air.

Continual use of carburetor heat should be avoided because of a loss of power and a noticeable variation of the fuel mixture when the heated air is supplied to the engine. High temperatures also favor detonation and pre-ignition, both of which must be avoided if normal service life is to be expected from the engine.

Note: When the carburetor is supplied with heated air, the mixture may become too rich because the air density decreases as temperature increases. If necessary, lean the mixture to have a smooth running engine.

Follow these general rules when using carburetor heat:
1. Takeoff : Takeoff should be made with the carburetor heat control in the full cold position (in). The possibility of icing at full throttle is very remote.
2. Flight Operation: The carburetor air heat control should be left in the cold position during normal flight operations. During all flight conditions, however, monitor the carburetor air temperature indicator and use carburetor heat to keep the temperature above the yellow arc.
Note: Under certain environmental conditions (damp, cloudy, or foggy days), carburetor icing is the most likely.

There are two instances in flight where carburetor heat must be used:
a. If the carburetor air temperature is noted decreasing into the yellow arc, use carburetor heat as necessary to maintain a temperature above the caution range (mixture leaning may be required for smooth engine operation).

b. If actual carburetor icing is suspected (drop in manifold pressure, etc), apply full carburetor heat and open the throttle (mixture leaning will be required to obtain smooth engine operation). The application of carburetor heat will result in an additional drop in manifold pressure, but the drop will be regained as the ice is melted out of the induction system. Once the ice is melted, partial heat may be used to keep the mixture temperature above the freezing point.

3. Landing : In making an approach for a landing, the carburetor heat control should generally be in the cold position. However, if icing conditions are suspected, the heat should be applied.

In the event that full power is required (as for a go-around), the carburetor heat control should be returned to full cold after full power application.

WARNING

Should the engine stop because of carburetor icing, the application of carburetor heat will not melt the ice since there is no suction of the hot air into the induction system. For this reason, it is essential to detect the presence of carburetor icing early to prevent engine failure.

ELECTRICAL POWER SUPPLY SYSTEM
(FIGURE 1-11)

The 28 volt, direct current (DC) electrical system is a single-conductor type, using the aircraft structure as a ground return line. The electrical power, maintained at a constant voltage by the voltage regulator, is supplied by an engine-driven alternator. A 24V lead acid battery is provided as an emergency source of electrical power and for aircraft starting. Most owners have switched to either a Concord RG24-11M battery or two Gil Gel-Cell batteries.

On the ground, the aircraft may be connected to a (28V DC and 150A) external power source by means of the external power receptacle located on the left side of the fuselage.

Electrical power is distributed by three bus bars: the primary bus, the secondary bus, and the radio bus. The primary bus distributes power to aircraft circuits through push-pull type circuit breakers. The secondary bus is connected to the primary bus and distributes electrical power to the aircraft circuits through toggle-type circuit breakers.

The radio bus is powered from the primary bus through the avionics master switch circuit breaker. In case of failure of the avionics master switch, the radio bus may also be powered by means of the emergency avionics master switch toggle-type circuit breaker. The electrical components powered by the radio bus are protected by push-pull type circuit breakers.

CIRCUIT BREAKERS

The circuit breakers protect the power system by disengaging automatically whenever an overloaded or short circuit exists.

CAUTION: Circuit breakers should not be pulled or reset without a thorough understanding of all the effects and results. Do no reset a circuit breaker more than once whenever there is power on the aircraft.

The push-pull type circuit breakers are located on the lower left side of the instrument panel. The toggle type circuit breakers are used in normal operation as component switches. The battery and alternator switches are located in the upper center of the instrument panel. All of the others are located on the lower left side of the instrument panel.

Refer to figure 1-12 for a description of the idividual circuit breakers.

The electrical system controls and indicators are explained in Figure 1-13.

LANDING GEAR

The aircraft is equipped with a retractable tricycle landing gear system which consists of two main gear and a nose gear. The landing gear position is controlled by the landing gear handle in the cockpit. When the handle is placed in the desired position, an electric actuator raises or lowers the gear through mechanical linkages consisting of control rods, bellcranks, and drag links. Each gear is mechanically connected to a door which matches the movement of the gear and encloses the gear compartment when the landing gear is retracted.

When the nose gear is extended, the rudder pedals steer the nosewheel. During retraction, the nosewheel automatically returns to the centered position.

The landing gear system requires approximately 7 seconds for extension or retraction. The landing gear circuit is powered by the primary bus through the LDG PWR circuit breaker.